1. Field of the Invention
The present invention relates in general to a bridged network and, in particular, to a network node (bridge) and method that can re-map a default VLAN to a high availability VLAN when a special MAC DA packet is received.
2. Description of Related Art
The following abbreviations are herewith defined, at least some of which are referred to in the ensuing description of the prior art and the preferred embodiment of the present invention.
CAMContent Addressable MemoryDADestination AddressMACMessage Authentication CodePCPersonal ComputerVLANVirtual Local Area NetworkVLAN_IDVLAN Identifier
Referring to FIG. 1A (PRIOR ART), there is shown an exemplary bridged network 100 which has two network nodes 102 and 104 that enable communications between multiple stations/servers 106a, 106b . . . 106e. In this bridged network 100, assume that ingress station 106a, egress server 106b, egress server 106c, ingress station 106d and data storage server 106e are all members of the same VLAN. As such, these stations/servers 106a, 106b . . . 106e are able to communicate with one another because they belong to the same bridging domain. A discussion about how these stations/servers 106a, 106b . . . 106e are able to communicate with one another is provided next.
In this example, assume the ingress station 106a (e.g., PC 106a) sends a packet 108 which is received at a port 110a within network node 102. Then, a CAM/processor 112 within the network node 102 performs a VLAN classification and determines that port 110a (associated with ingress station 106a), port 110b (associated with egress station 106b) and interswitch port 110f (indirectly associated with egress server 106c, ingress station 106d and data storage server 106e) are members of the same VLAN. In particular, the CAM/processor 112 performs a table look-up using a MAC DA within packet 108 and determines that ports 110a, 110b and 110f are members of the same VLAN. The network node 102 then forwards (or floods) copies of packet 108 to ports 110b and 110f. In this way, the egress server 106b (e.g., firewall 106b) receives a copy of packet 108. And, the network node 104 which is connected to interswitch port 110f receives a copy of packet 108.
The network node 104 also has a CAM/processor 114 which upon receiving packet 108 performs a VLAN classification and in this example it determines that interswitch port 110f and ports 110c, 110d and 110e (associated with egress server 106c, ingress station 106d and data storage server 106e) are members of the same VLAN. In particular, the CAM/processor 114 performs a table look-up using the MAC DA within packet 108 and determines that ports 110c, 110d, 110e and 110f are members of the same VLAN. The network node 104 then forwards (or floods) copies of packet 108 to ports 110c, 110d and 110e. In this way, the egress server 106c (e.g., firewall 106c) which is connected to port 110c receives a copy of packet 108. The ingress station 106d (e.g., PC 106d) which is connected to port 110d receives a copy of packet 108. And, the data storage server 106e which is connected to port 110e receives a copy of packet 108.
However, in some applications, the egress servers 106b and 106c are the only devices that need to obtain a copy of packet 108 if it contained a special MAC DA (as opposed to a normal MAC DA) and if it originated from one of the ingress stations 106a and 106d (e.g., PCs 106a and 106d). For instance, the egress servers 106b and 106c (e.g., firewalls 106b and 106c) may need a copy of this special MAC DA packet 108 so they can perform a routing update. As can be appreciated, it is not very efficient if a special MAC DA packet 108 originating from an ingress station 106a is forwarded to the ingress station 106d and the data storage server 106e. Because, the ingress station 106d and the data storage server 106e do not need a copy of the special MAC DA packet 108. One possible solution to this problem is described below with respect to FIG. 1B (PRIOR ART).
Referring to FIG. 1B (PRIOR ART), there is shown the exemplary bridged network 100 in which the ingress stations 106a and 106d and egress servers 106b and 106c have been made members of a special VLAN in an attempt to address the aforementioned problem. In this scheme, when ingress station 106a (for example) sends a packet 108 (containing a normal/special MAC DA), then the ingress station 106d and egress servers 106b and 106c each receive a copy of the packet 108 (shown in FIG. 1B). Likewise, when ingress station 106d sends a packet 108 (containing a normal/special MAC DA), then the ingress station 106a and egress servers 106b and 106c each receive a copy of packet 108 (not shown in FIG. 1B). This approach has several problems. First, putting the ingress stations 106a and 106d and egress servers 106b and 106c within the special VLAN removes them from the VLAN which included all of the stations/servers 106a, 106d . . . 106e (see FIG. 1A). This is a problem because it is desirable to maintain the connectivity between all of these stations/servers 106a, 106b . . . 106e. Second, if the network nodes 102 and 104 flood copies of the packet 108 within this special VLAN then a copy of the packet 108 will be sent to one ingress station 106a or 106d which is not desirable since only the egress servers 106b and 106c need a copy of this packet 108. Accordingly, there has been and is still a need for a solution which can address this particular problem associated with the traditional bridged network. This need and other needs are addressed by the network node and method of the present invention.